[Loadstone] WAAS/EGNOS question

Mikolaj Rotnicki mikolaj-rotnicki at o2.pl
Tue Mar 27 19:50:14 BST 2007


Hi Gabriel and Paul and all other LS users ofcourse *smile*.

WAAS and EGNOS are examples of Satellite Based Augmentation Systems 
(SBAS).You cen find more here: 
http://en.wikipedia.org/wiki/Satellite_based_augmentation_system#Satellite_Based_Augmentation_System

They are not part of the GPS sestem (ran by the US Department of Defence), 
although WAAS and EGNOS satellites send differencial correction signal on 
the similar frequencies as GPS satellites.

EGNOS (European Geostationary Navigation Overlay Service) is ran by ESA 
(European Space Agency).
More on EGNOS here:
http://en.wikipedia.org/wiki/European_Geostationary_Navigation_Overlay_Service
I consists of few (iI think 3) satellites. One covering Atlantic ocean, one 
covering Europe and Africa, and one covering Indian ocean and the middle 
east.

Unlike GPS satellites, the WAAS/EGNOS satellites are geostationary which 
means thay are placed above a a specific point over Earth's surface (similar 
to telecom satellites). This means that for example in Europe they are 
visible low over the souther  horizon, about 20 degrees. There fore it is 
sometimes difficult for the receiver to get thair signal aspecially when the 
southern part of the sky is bscured by high buildings.

I live in Poland. I have never got a differencial GPS fix, although I have 
condirmed that my Nokia LD-3W receives the EGNOS signal (using a PC software 
Visual GPS, available here for free http://www.visualgps.net/VisualGPS/ - 
unforunately i think it is not accessible for screenreaders although you may 
try, as I am partly sighted person and do not use screenreader)

WAAS (Wide Area Augmentation System) is ran by FAA (Federal Aviation 
Administration), also consists of few satellites, covering area ranging from 
Hawaii through the North and South America, to the Atlantic Ocean).
You can find more on WAAS here: http://en.wikipedia.org/wiki/WAAS

There is also a third satellite based augmentation system called (MFSAT) 
Multi-Functional Transport Satellite ran by Japan and Australia - covering 
that part of the world. You cand find out more about MFSAT here: 
http://en.wikipedia.org/wiki/Multi-Functional_Transport_Satellite

All three systems are compatible with each other, as they transmit the 
differencial correction in same way and on same frequencies, although each 
covers different part of the world.


-----
Pozdrawiam
Mikolaj Rotnicki

----- Original Message ----- 
From: "Gabriel Battaglia" <gabriele.battaglia at gmail.com>
To: <loadstone at loadstone-gps.com>
Sent: Tuesday, March 27, 2007 7:03 PM
Subject: Re: [Loadstone] WAAS/EGNOS question


> Hi Paul, you did several interesting questions and I'm really very
> interested to read answers me too even do I maybe know some of information
> you're looking for.
> I know for instance, please everybody correct me if it is not, that
> WAAS/EGNOS covers all the globe cause it's part of GPS system, using it or
> not dipends on how many satellites your receiver is peeking and if it is
> able or not to receive WAAS/EGNOS correction.
> With WAAS/EGNOS active, your position will be calculated with 3 or 4 
> meters
> maximum of derive, instead of the 15/30 meters you have right now.
>
> I saw just one time since the 3rd november 2006, a differential GPS on my
> loadstone, often I get 9 or 10 satellites getting an accuracy of 0.8 but 
> no
> differential GPS on. Why? Unfortunately I don't know.
>
> It's exactly for this reason I tried to send command directly to my 
> receiver
> using a software called SiRfDemo, just to be sure that receiver has it
> turned on.
> Unfortunately I made mistake changing operative mode to the receiver and 
> now
> I've put its battery away in order to reset it.
>
> I really appreciate to read some more about WAAS/EGNOS... My question is 
> so
> simple: if it exists, why we can not use it?
>
> Thanks for all explanations.
> Gabriel.
>
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>
>
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